 /*
  * $Header: /cvshome/build/org.osgi.service.wireadmin/src/org/osgi/service/wireadmin/WirePermission.java,v 1.13 2006/07/12 21:22:14 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2002, 2006). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package org.osgi.service.wireadmin;

 import java.io.IOException ;
 import java.security.*;
 import java.util.Enumeration ;
 import java.util.Hashtable ;

 /**
  * Permission for the scope of a <code>Wire</code> object. When a
  * <code>Envelope</code> object is used for communication with the <code>poll</code>
  * or <code>update</code> method, and the scope is set, then the <code>Wire</code>
  * object must verify that the Consumer service has
  * <code>WirePermission[name,CONSUME]</code> and the Producer service has
  * <code>WirePermission[name,PRODUCE]</code> for all names in the scope.
  * <p>
  * The names are compared with the normal rules for permission names. This means
  * that they may end with a "*" to indicate wildcards. E.g. Door.* indicates all
  * scope names starting with the string "Door". The last period is required due
  * to the implementations of the <code>BasicPermission</code> class.
  *
  * @version $Revision: 1.13 $
  */
 final public class WirePermission extends BasicPermission {
     static final long serialVersionUID = -5583709391516569321L;
     /**
      * The action string for the <code>PRODUCE</code> action: value is "produce".
      */
     public static final String PRODUCE = "produce";
     /**
      * The action string for the <code>CONSUME</code> action: value is "consume".
      */
     public static final String CONSUME = "consume";
     private final static int ACTION_PRODUCE = 0x00000001;
     private final static int ACTION_CONSUME = 0x00000002;
     private final static int ACTION_ALL = ACTION_PRODUCE
                                                         | ACTION_CONSUME;
     private final static int ACTION_NONE = 0;
     /**
      * The actions mask.
      */
     private transient int action_mask = ACTION_NONE;
     /**
      * The actions in canonical form.
      *
      * @serial
      */
     private String actions = null;

     /**
      * Create a new WirePermission with the given name (may be wildcard) and
      * actions.
      * @param name Wire name.
      * @param actions <code>produce</code>, <code>consume</code>
      * (canonical order).
      */
     public WirePermission(String name, String actions) {
         this(name, getMask(actions));
     }

     /**
      * Package private constructor used by WirePermissionCollection.
      *
      * @param name class name
      * @param mask action mask
      */
     WirePermission(String name, int mask) {
         super(name);
         init(mask);
     }

     /**
      * Called by constructors and when deserialized.
      *
      * @param mask action mask
      */
     private void init(int mask) {
         if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
             throw new IllegalArgumentException ("invalid action string");
         }
         action_mask = mask;
     }

     /**
      * Parse action string into action mask.
      *
      * @param actions Action string.
      * @return action mask.
      */
     private static int getMask(String actions) {
         boolean seencomma = false;
         int mask = ACTION_NONE;
         if (actions == null) {
             return mask;
         }
         char[] a = actions.toCharArray();
         int i = a.length - 1;
         if (i < 0)
             return mask;
         while (i != -1) {
             char c;
             // skip whitespace
 while ((i != -1)
                     && ((c = a[i]) == ' ' || c == '\r' || c == '\n'
                             || c == '\f' || c == '\t'))
                 i--;
             // check for the known strings
 int matchlen;
             if (i >= 6 && (a[i - 6] == 'p' || a[i - 6] == 'P')
                     && (a[i - 5] == 'r' || a[i - 5] == 'R')
                     && (a[i - 4] == 'o' || a[i - 4] == 'O')
                     && (a[i - 3] == 'd' || a[i - 3] == 'D')
                     && (a[i - 2] == 'u' || a[i - 2] == 'U')
                     && (a[i - 1] == 'c' || a[i - 1] == 'C')
                     && (a[i] == 'e' || a[i] == 'E')) {
                 matchlen = 7;
                 mask |= ACTION_PRODUCE;
             }
             else
                 if (i >= 6 && (a[i - 6] == 'c' || a[i - 6] == 'C')
                         && (a[i - 5] == 'o' || a[i - 5] == 'O')
                         && (a[i - 4] == 'n' || a[i - 4] == 'N')
                         && (a[i - 3] == 's' || a[i - 3] == 'S')
                         && (a[i - 2] == 'u' || a[i - 2] == 'U')
                         && (a[i - 1] == 'm' || a[i - 1] == 'M')
                         && (a[i] == 'e' || a[i] == 'E')) {
                     matchlen = 7;
                     mask |= ACTION_CONSUME;
                 }
                 else {
                     // parse error
 throw new IllegalArgumentException ("invalid permission: "
                             + actions);
                 }
             // make sure we didn't just match the tail of a word
 // like "ackbarfregister". Also, skip to the comma.
 seencomma = false;
             while (i >= matchlen && !seencomma) {
                 switch (a[i - matchlen]) {
                     case ',' :
                         seencomma = true;
                     /* FALLTHROUGH */
                     case ' ' :
                     case '\r' :
                     case '\n' :
                     case '\f' :
                     case '\t' :
                         break;
                     default :
                         throw new IllegalArgumentException (
                                 "invalid permission: " + actions);
                 }
                 i--;
             }
             // point i at the location of the comma minus one (or -1).
 i -= matchlen;
         }
         if (seencomma) {
             throw new IllegalArgumentException ("invalid permission: " + actions);
         }
         return mask;
     }

     /**
      * Checks if this <code>WirePermission</code> object <code>implies</code> the
      * specified permission.
      * <P>
      * More specifically, this method returns <code>true</code> if:
      * <p>
      * <ul>
      * <li><i>p </i> is an instanceof the <code>WirePermission</code> class,
      * <li><i>p </i>'s actions are a proper subset of this object's actions,
      * and
      * <li><i>p </i>'s name is implied by this object's name. For example,
      * <code>java.*</code> implies <code>java.home</code>.
      * </ul>
      *
      * @param p The permission to check against.
      *
      * @return <code>true</code> if the specified permission is implied by this
      * object; <code>false</code> otherwise.
      */
     public boolean implies(Permission p) {
         if (p instanceof WirePermission) {
             WirePermission target = (WirePermission) p;
             return ((action_mask & target.action_mask) == target.action_mask)
                     && super.implies(p);
         }
         return false;
     }

     /**
      * Returns the canonical string representation of the actions. Always
      * returns present actions in the following order: <code>produce</code>,
      * <code>consume</code>.
      *
      * @return The canonical string representation of the actions.
      */
     public String getActions() {
         if (actions == null) {
             StringBuffer sb = new StringBuffer ();
             boolean comma = false;
             if ((action_mask & ACTION_PRODUCE) == ACTION_PRODUCE) {
                 sb.append(PRODUCE);
                 comma = true;
             }
             if ((action_mask & ACTION_CONSUME) == ACTION_CONSUME) {
                 if (comma)
                     sb.append(',');
                 sb.append(CONSUME);
             }
             actions = sb.toString();
         }
         return actions;
     }

     /**
      * Returns a new <code>PermissionCollection</code> object for storing
      * <code>WirePermission</code> objects.
      *
      * @return A new <code>PermissionCollection</code> object suitable for storing
      * <code>WirePermission</code> objects.
      */
     public PermissionCollection newPermissionCollection() {
         return new WirePermissionCollection();
     }

     /**
      * Determines the equalty of two <code>WirePermission</code> objects.
      *
      * Checks that specified object has the same name and actions as this
      * <code>WirePermission</code> object.
      *
      * @param obj The object to test for equality.
      * @return true if <code>obj</code> is a <code>WirePermission</code>, and has
      * the same name and actions as this <code>WirePermission</code>
      * object; <code>false</code> otherwise.
      */
     public boolean equals(Object obj) {
         if (obj == this) {
             return true;
         }
         if (!(obj instanceof WirePermission)) {
             return false;
         }
         WirePermission p = (WirePermission) obj;
         return (action_mask == p.action_mask) && getName().equals(p.getName());
     }

     /**
      * Returns the hash code value for this object.
      *
      * @return Hash code value for this object.
      */
     public int hashCode() {
         return getName().hashCode() ^ getActions().hashCode();
     }

     /**
      * Returns the current action mask. Used by the WirePermissionCollection
      * object.
      *
      * @return The actions mask.
      */
     int getMask() {
         return action_mask;
     }

     /**
      * Returns a string describing this <code>WirePermission</code>. The
      * convention is to specify the class name, the permission name, and the
      * actions in the following format:
      * '(org.osgi.service.wireadmin.WirePermission &quot;name&quot;
      * &quot;actions&quot;)'.
      *
      * @return information about this <code>Permission</code> object.
      */
     public String toString() {
         StringBuffer sb = new StringBuffer ();
         sb.append('(');
         sb.append(getClass().getName());
         sb.append(" \"");
         sb.append(getName());
         sb.append("\" \"");
         sb.append(getActions());
         sb.append("\")");
         return sb.toString();
     }

     /**
      * WriteObject is called to save the state of the ServicePermission to a
      * stream. The actions are serialized, and the superclass takes care of the
      * name.
      */
     private synchronized void writeObject(java.io.ObjectOutputStream s)
             throws IOException {
         // Write out the actions. The superclass takes care of the name
 // call getActions to make sure actions field is initialized
 if (actions == null)
             getActions();
         s.defaultWriteObject();
     }

     /**
      * readObject is called to restore the state of the ServicePermission from a
      * stream.
      */
     private synchronized void readObject(java.io.ObjectInputStream s)
             throws IOException , ClassNotFoundException {
         // Read in the action, then initialize the rest
 s.defaultReadObject();
         init(getMask(actions));
     }
 }
 /**
  * A <code>WirePermissionCollection</code> stores a set of <code>WirePermission</code>
  * permissions.
  */

 final class WirePermissionCollection extends PermissionCollection {
     static final long serialVersionUID = 2617521094909826016L;
     /**
      * Table of permissions.
      *
      * @serial
      */
     private Hashtable permissions;
     /**
      * Boolean saying if "*" is in the collection.
      *
      * @serial
      */
     private boolean all_allowed;

     /**
      * Creates an empty WirePermissionCollection object.
      *
      */
     public WirePermissionCollection() {
         permissions = new Hashtable ();
         all_allowed = false;
     }

     /**
      * Adds a permission to this PermissionCollection.
      *
      * @param permission The Permission object to add.
      *
      * @throws IllegalArgumentException If the permission is not a
      * WirePermission object.
      *
      * @throws SecurityException If this PermissionCollection has been marked
      * read-only.
      */
     public void add(Permission permission) {
         if (!(permission instanceof WirePermission))
             throw new IllegalArgumentException ("invalid permission: "
                     + permission);
         if (isReadOnly())
             throw new SecurityException ("attempt to add a Permission to a "
                     + "readonly PermissionCollection");
         WirePermission p = (WirePermission) permission;
         String name = p.getName();
         WirePermission existing = (WirePermission) permissions.get(name);
         if (existing != null) {
             int oldMask = existing.getMask();
             int newMask = p.getMask();
             if (oldMask != newMask) {
                 permissions.put(name, new WirePermission(name, oldMask
                         | newMask));
             }
         }
         else {
             permissions.put(name, permission);
         }
         if (!all_allowed) {
             if (name.equals("*"))
                 all_allowed = true;
         }
     }

     /**
      * Determines if a set of permissions implies the permissions expressed in
      * <code>permission</code>.
      *
      * @param permission The Permission object to compare.
      *
      * @return <code>true</code> if <code>permission</code> is a proper subset of a
      * permission in the set; <code>false</code> otherwise.
      */
     public boolean implies(Permission permission) {
         if (!(permission instanceof WirePermission))
             return false;
         WirePermission p = (WirePermission) permission;
         WirePermission x;
         int desired = p.getMask();
         int effective = 0;
         // short circuit if the "*" Permission was added
 if (all_allowed) {
             x = (WirePermission) permissions.get("*");
             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return true;
             }
         }
         // strategy:
 // Check for full match first. Then work our way up the
 // name looking for matches on a.b.*
 String name = p.getName();
         x = (WirePermission) permissions.get(name);
         if (x != null) {
             // we have a direct hit!
 effective |= x.getMask();
             if ((effective & desired) == desired)
                 return true;
         }
         // work our way up the tree...
 int last, offset;
         offset = name.length() - 1;
         while ((last = name.lastIndexOf(".", offset)) != -1) {
             name = name.substring(0, last + 1) + "*";
             x = (WirePermission) permissions.get(name);
             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return (true);
             }
             offset = last - 1;
         }
         // we don't have to check for "*" as it was already checked
 // at the top (all_allowed), so we just return false
 return false;
     }

     /**
      * Returns an enumeration of all the Permission objects in the container.
      *
      * @return Enumeration of all the Permission objects.
      */
     public Enumeration elements() {
         return permissions.elements();
     }
 }

